As part of our effort to improve the tracking options with Snowplow, we recently released a new feature called Anonymous Tracking. This is a two part release, requiring an updated JavaScript Tracker (v2.17.x) and Stream Collector (v2.1.x).
Stream Collector v2.1.1
In version 2.1.1 we identified an issue where in a scenario where anonymous tracking was turned on, then off and then back on again users could still be identified via the “leftover” cookie in their browser which populates the network_userid field. This user had previously allowed their user identifiers to be captured, which meant the cookie was stored in the browser from the collector and subsequently is automatically sent, by the browser, with all future requests.
Stream Collector v2.1.2
To resolve this issue, we introduced 2.1.2 which removed the network_userid in all cases when anonymous tracking was enabled in the JavaScript Tracker. Unfortunately, this causes a downstream issue which leads to the event becoming a bad row (often referred to as a failed event). To prevent this, if you are using v2.1.2, you should avoid enabling the Anonymous Tracking features in the JavaScript tracker.
Stream Collector v2.2.0
The behaviour from 2.1.2 was carried over in the subsequent 2.2.0 release.
Next Steps
We are currently recommending that users do not enable Anonymous Tracking in the JavaScript Tracker until we have resolved this issue fully in our upcoming release. We have begun work on this in earnest and will have further updates soon which we will publish here.
We’re sorry this fell through our testing. The v2.1.1 issue was an untested edge case (which we address with additional tests in v2.1.2) and the other uncovered a gap in our integration testing. We’re addressing the latter with urgency.